1. Field of the Invention
The present invention relates to a subscriber network system and method of setting in-device information in a concentrator thereof, and particularly relates to a method of setting in-device information in an ATM (Asynchronous Transfer Mode) concentrator in a subscriber network system comprised of an ATM exchange and an ATM concentrator disposed at remote locations.
2. Background Art
In the subscriber network system comprised of an ATM exchange arranged in a central telephone station and an ATM concentrator at remote locations, it is preferable that the ATM concentrators are provided in large quantities close to subscribers are simple in structure and are obtainable at a reduced cost.
When considering a multi-cast service which distributes a signal with the same content to a plurality of subscribers, it is preferable to distribute the signal at the ATM concentrator which forms branching points to each subscriber from the point of view of efficient utilization of transmission band.
When it is desired to satisfy the above condition in a SVC (Switched Virtual Connection) service which executes dynamic signal setting, it becomes necessary to send and receive the path setting information from an ATM exchange implementing signaling processing to each ATM concentrator.
For example, as shown in FIG. 7, in a subscriber network system comprising an ATM exchange 100 and an ATM concentrator 200, one of the solutions will be the use of a communication line (a control information transmission line) between a device control portion 150 in the ATM exchange 100 and a device control portion 270 in the ATM concentrator 200.
Here, the ATM exchange 100 is connected to the ATM network 300 through the ATM transmission line 1, and is also connected to the ATM concentrator 200 through the ATM transmission line 2. In addition, the ATM concentrators are connected to a plurality of subscribers through the ATM transmission lines 3-1 to 3-n. 
The ATM exchange 100 comprises a cell switch 110, a call control processing portion 120, an device control portion 150, and the ATM concentrator 200 comprises a cell inserting and separating portion 210, a filter table 230, cell filters 24-1 to 24-n, and a device control portion 270.
A technique using a construction similar to the above subscriber network system has been disclosed in Japanese Patent Application, First Publication No. Hei 9-168014. This application discloses a method in which signaling is carried out by one ATM exchange, and line information is set for small ATM exchange.
In Japanese Patent Application, First Publication No. Hei 9-238148, a system is disclosed in which a control cell is used for controlling a subscriber side device (ONU: Optical Network Unit) in a PSD (Passive Double Star) system.
In the above system, although the control cell is used for controlling the subscriber side device, the control cell is originally used for monitoring the state of the subscriber side device and is not used for directly setting the subscriber side device.
Since an exclusive transmission line (control information transmission line) is used for transmission between the device control portion of the ATM exchange and the device control portion of the ATM concentrator in the above be, described conventional subscriber network system, problems are encountered in that it takes time until the set path is reflected when a high level control signal path is adopted, in that the ATM concentrator is required to execute complicated processing, and in that the cost of the concentrators increases.
Therefore, the objects of the present invention are to solve the above problems, and to provide a subscriber network system which is capable of reducing the response time and which is capable of reducing the device cost.